A query can be prepared under one access context and approved under another. A data-source grant may have been revoked. The requester's organization may have changed. Table permissions may no longer match the original request.
The approval path therefore checks the current right to execute, not only the presence of an earlier approval screen. It verifies the request's owner and validation state, rechecks data-source and table access, and compares relevant organization context. A prepared query can stop at this boundary if the context has changed.
Execution is also constrained closer to the database. The collector opens a read-only connection and transaction and sets a timeout before running a SELECT. Where an explain plan is available, configured estimated-cost and row gates can stop an expensive plan before execution. These gates are conditional: unavailable plan estimation is reported and should not be described as a universally enforced cost guarantee.
The design principle is separation of responsibility. Model output describes a possible query. Authorization decides whether it may proceed. The execution adapter applies data-layer restrictions. No one stage is a substitute for the others.